The present invention relates to automated marking devices and, more specifically, to an automated location marking tool for attachment to a fiber placement head on a fiber placement machine.
A fiber placement machine (FPM) is an NC programmable and controlled machine with very high accuracy that is calibrated for each tool that is loaded. The FPM has a fiber placement head that is used to place bands of uncured epoxy impregnated composite fibers (hereinafter referred to as fibers) on a layout mandrel or tool surface mounted in the FPM. The FPM in conjunction with the fiber placement head is fully matriculating. The mandrel or tool surface can be of various shapes and sizes and, in some instances, can be a honeycomb core. The various shapes can include complex contours and features. NC programming of the FPM and positioning of the fiber placement head allows the ability to precisely locate any position on a defined mandrel/tool surface.
During the fiber placement process it is necessary to accurately locate, mark and identify areas or locations for manually (hand) placed ply details, honeycomb core locations, inspection or other details to be attached before or after the fibers have cured. The size and shape of most parts that are placed on the fibers makes it very difficult to accurately locate and mark a given location on the layout surface. Markings may also be required to be made on other materials which cover the fibers, such as film adhesives or peel plies.
Previous attempts to facilitate accurate and efficient marking of detail locations have not been successful. For example, optical laser template systems have been used to attempt to accurately locate and mark the detail locations on the fiber surface. While some success has been achieved on small, simple parts, the use of the optical laser template on large or complex parts has proved to be too cumbersome and ergonomically unfeasible. The use of the optical laser template system required an excessive amount of time and the required accuracy on a large part with multiple standard tooling guides could not be achieved. Manually marking the detail locations on the lay-up surface also proved to be not efficient and very time consuming. Additionally, the manual marking also proved to be prone to location errors.
Therefore, what is needed is an efficient way to accurately apply marks on the fiber surface regardless of the size or complexity of the detail locations. Because the FPM has the ability to accurately and efficiently locate any point on the fiber surface, it is desirable to utilize the FPM to make the marks on the fiber surface. Therefore, a marking tool for attachment to the FPM that can be used to mark the detail locations is needed.
Furthermore, the fiber surface and underlying structure, such as a honeycomb core, are fragile and can be easily damaged during the detail location marking procedure. Because the fiber surface and underlying structure are fragile, the marking tool designed to be used with the FPM must be capable of doing so without damaging the fiber surface and the underlying structure. For example, in a typical application the fibers are applied to a honeycomb core and the marking tool is then used to apply detail locations on the fibers or other materials that are on top of the honeycomb core. Because the fibers are not cured if too much pressure is applied by the marking tool on the fibers, the marking tool can penetrate the fibers and catch an edge of a honeycomb core cell and potentially cause significant damage or tearing of the cell. Therefore, what is needed is a marking tool that can be used on the FPM that reduces and/or eliminates the possibility of damage being caused to the fibers and the underlying structure.
Some FPMs are equipped with a laser that is programmed to show the location of details on the surface of the fibers. However, the laser, while being capable of pin pointing discrete points of the details on the fiber surface, does not leave any type of mark that can later be used to attach the details to the fiber surface. Therefore, the laser is presently used to inspect the location and accuracy of previously marked details on the fiber surface. That is, after the details have been marked on the fiber surface the NC program that controls the movement of the laser is run and the laser will trace the outline of the detail locations by moving from discrete point to discrete point along the details and a person can visually observe the laser beam as it moves along the detail location to determine if the detail markings are aligned with the laser beam striking the fiber surface.
The use of a FPM with a laser can aid in the use of the FPM to make marks of detail locations on the fiber surface. Because FPMs with a laser have an NC program that controls the laser""s position so that the laser can illuminate the location of the details, the NC program, with some modification, might be capable of being utilized to operate the marking tool attached to the FPM. Therefore, it is desirable to have a marking tool that can be attached to the FPM and utilize the existing NC program (with some modifications) written for the laser to control the operation of the marking tool.
The present invention is directed to a method and apparatus for using an NC controlled FPM to apply detail markings on a work piece in the FPM, in accordance with preferred embodiments of the present invention. In one preferred embodiment, a compliant marking tool is attached to a FPM. The marking tool makes marks on the work piece without damaging the work piece. The marking tool has a flexible member that is configured and adapted to flex in response to the contact between the marking tool and the work piece as the marking tool makes marks on the work piece. The flexing of the flexible member allows the marking tool to follow the contour of the work piece. The marking tool has a holder that is pivotally connected to the flexible member. The pivotable connection allows the holder to pivot relative to the flexible member. A marking member is positioned in the holder. The marking member has a tip that is capable of making marks on the work piece when the tip contacts the work piece. The marking member is positioned in the holder so that the tip can contact the work piece when the FPM is being used to operate the marking tool.
Preferably, the tip extends longitudinally from the marking member and the marking member can move longitudinally relative to the holder in response to the tip contacting the work piece. Even more preferably, the marking member is biased to resist longitudinal movement in response to the tip contacting the work piece. Additionally, it is preferred that the tip be offset from an axis of rotation of the pivot connection between the holder and the flexible member. Furthermore, it is preferred that the pivot connection between the flexible member and the holder be biased toward a predetermined orientation. The marking tool may also have a stop that limits the pivoting of the holder relative to the flexible member.
The flexible member can also be configured and adapted to allow the tip to vibrate as the tip travels along the surface of the work piece. The vibrating of the tip facilitates a flow of marking material to the tip.
The marking tool is preferably attached to the FPM in the location where the compaction roller is normally attached to the FPM. When the marking tool is attached to the FPM, the marking tool is attached so that the tip is in a known position relative to the FPM axis so that the marking tool can be controlled by an NC program that operates the FPM.
The marking tool can also be attached so that the tip is offset a known distance from the compaction roller. When the tip is offset a known distance from the compaction roller, the NC program that controls the compaction roller can be used to control the movement of the tip by programming an offset from the compaction roller into the NC program. The use of the NC program written for the compaction roller avoids the necessity of writing a new NC program for the marking tool.
If the FPM has a laser attached to the FPM, it is preferred that the marking tool be mounted on the FPM so that a center line of the tip is inline with the laser beam being emitted by the laser and the tip is offset a known distance from the laser so that the NC program that controls the laser can be used to control the movement of the tip by programming the offset from the laser. Because the laser is at a known position relative to the FPM, the positioning of the tip of the marking tool at a known distance from the laser causes the tip to be at a known position relative to the FPM. This enables the existing NC program that was written to operate the laser to be used to operate the marking tool. The use of the NC program written for the laser avoids the necessity of writing a new NC program for the marking tool.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.